MINDEN, Nev. -- Pilots and rescue teams searching for missing adventurer Steve Fossett expanded their target area to 10,000 square miles of California and Nevada on Thursday and planned to use sonar to search a lake where the multimillionaire could have crashed.
"As you can imagine, trying to make that needle stand out in a haystack that big is going to be a real challenge," Nevada Civil Air Patrol Maj. Cynthia Ryan said. "It's going to be frustrating for a lot of people who were hoping for results early on."
Ryan said the intensive aerial, ground and water search for Fossett could last two weeks or longer. "Four days into it, we are still scratching the surface," she said.
Air crews were making multiple passes over the same areas but at different times of the day to check under different lighting conditions. The jagged peaks and steep canyons of the region cast shadows that can interfere with the views of search crews.
Nevada Highway Patrol Trooper Chuck Allen said a sonar-equipped boat would search Walker Lake, about 15 miles from the Flying M Ranch where Fossett took off on Monday, to determine whether his plane could be beneath the surface. The lake stretches for about 18 miles.
"It will allow people on the boat to rule this area out as a potential place the plane could have ended up," he said Thursday.
In all, the expanded search area is 200 to 300 miles wide and stretches 120 miles south from the small town of Yerington, Nev., to Bishop, Calif., on the eastern side of the Sierra Nevada. In all, it's an area about the size of Massachusetts.
Ryan said it now also includes the Black Rock Desert far to the north, where land speed records have been attempted in the past.
Fossett was on a mission to study possible dry lake beds for a planned attempt to break the world land speed record when he disappeared on Monday.
"We're going to find this guy, but it's a big country," Civil Air Patrol Maj. Terry Vanzant said shortly before taking to the sky Thursday morning.
National Guard C-130s and helicopters with thermal imaging equipment searched the soaring peaks and sagebrush desert of northwest Nevada on Wednesday but failed to find anything new, Ryan said.
Fossett's friends, meanwhile, remained confident that the world-famous adventurer is alive. They point to his experience climbing some of the world's best-known peaks, including the Matterhorn in Switzerland.
"If anyone has to be lost out there, this man has the skills to survive," Ryan said Wednesday. "With water, he could live out there for two weeks."
Fossett's plane, a Bellanca Citabria Super Decathlon, carried both water and food, but there also were troubling signs: The missing plane's locator device had not sent a signal, there had been no communication from the plane's radio, and an emergency wristwatch Fossett wore to signal his location had not been activated.
Ryan said Thursday that the terrain could make communication difficult and the emergency devices might not be able to send out a signal properly if Fossett was deep in a canyon.
Some veteran pilots speculated he may have fallen victim to the treacherous Sierra Nevada winds that squeeze through the narrow canyons.
"There's been times when I've been flying in the wind and my blood turns cold," said Adam Mayberry, a private pilot and former spokesman for the Reno-Tahoe International Airport.
On Wednesday, the searchers were briefly encouraged when one aerial team spotted a downed aircraft it believed was Fossett's. But a helicopter crew determined the wreckage was from one of dozens of old downed planes that litter the region's canyons.
Fossett is familiar with danger and high-octane rescues, after years of breaking - or attempting to break - speed and distance records on land and by air. He has held 116 such records.
Fossett aborted a 1996 attempt to be the first person to circumnavigate the globe in a balloon when his electrical system failed. He landed in a farmer's field near Maine.
In August 1998, Fossett's balloon crashed into the Coral Sea about 500 miles off Australia's coast during his fourth attempt to circle the globe. It plunged 29,000 feet after it was struck by hail and lightning during a fierce storm.
He was rescued by the crew of a yacht days later.
Fossett finally succeeded in circumnavigating the globe in a balloon in 2002, and three years later became the first solo pilot to circle the globe in an airplane without refueling.
Professor Ray Arvidson, chairman of the Earth and Planetary Sciences Department at Washington University in St. Louis, worked at the ground operations center for three of Fossett's balloon flights.
"I'm worried," Arvidson said, "but this guy is a survivor."
On the Net:
Steve Fossett Challenges: http://www.stevefossett.com/
National Aviation Hall of Fame Fossett page: http://tinyurl.com/2mlbca